Color quality inspection and compensation for color LED display modules

The paper presents an automated color inspection and compensation solutions for color LED modules which are main components of a color LED display panel. Initially, a self-developed color optical sensing module and a colorimeter were used to measure the colors of LED pixels. After the color matching functions from the collected data was corrected by least-squares approximation method, the calibrated measured sensing module was applied to inspect the color characteristics of LED modules. And the chrominance and luminance data are well analyzed to perform a white light chrominance correction and luminance uniformity compensation for LED display modules. Some 2R1G1B LED modules (16×16 LEDs) from a local industry were verified in this study. The experimental results from the central 8×8 LEDs show that the average color difference of a target D65 white light with a chrominance of (0.1978, 0.4683) by using a 2R1G1B LED module is about 0.027006 before compensation, but the average color difference can be reduced to 0.003474 after it was compensated by using the proposed method. Meanwhile, the luminance difference was also reduced to less than 3.541%.